NAMA : DIRA PRATIWIKELAS : XII IPA 5ABSEN : 08

Meteor Showers ExplainedImagine a very cold comet consistently orbiting outer space. Because of the comets speed, there are particles that fall back behind it that are known as water vapor drags. These water vapor drags are composed of rocks from the comet itself and other compounds like frozen water, ammonia, methane and other volatile elements. When a particular comet gets near the sun which forms part of its orbit, some of these water vapor drags melt and are left out, and it eventually finds its way to meteoroid streams more commonly known as dust trails.Some of these dust trails subsequently veers into the orbit path of the Earth and when it hits the Earths atmosphere, it disintegrates and forms a meteor shower. The movements of these dust trails have been well studied and in fact the International Meteor Organization has come up with a Meteor Shower Calendar. The gravity of the planets surrounding the dust trails determine their movements, hence, IMO was able to compute its future locations. Meteor showers have tags and they are commonly named after the constellation where they are perceived to originate from.This type of meteor movement study and position calculation were first done by two astronomers, Arthur Matthew Weld Downing and George Johnstone Stoney. They set their observation on the comet 55P/Tempel-Tuttle and they were able to come up with a decent calculation which matched the computations of Adolf Berberich of the Royal Astronomical Computation Institute ( Konigles Astronomisches Rechen Institut ) of Berlin, Germany in one of his independent endeavors. However, the very first accurate meteor storms computation for the next 50 years was made by Finlands Esko Lyytinen, Robert McNaught, and David Asher.However, some dust trails may act abnormally when it reaches the atmosphere of certain planet. For instance, dust trails grazing on Jupiters atmosphere tend to act differently, some speed up and some decelerate creating sudden bursts of meteor showers, which is also known as braiding or clumping.

NAMA : DIRA PRATIWIKELAS : XII IPA 5ABSEN : 08How Your Eyes WorkVision begins when light rays are reflected off an object and enter the eyes through the cornea, the transparent outer covering of the eye. The cornea bends or refracts the raysthat pass through a round hole called the pupil. The iris, or colored portion of the eye that surrounds the pupil, opens and closes (making the pupil bigger or smaller) to regulate the amount of light passing through. The light rays then pass through the lens, which actually changes shape so it can further bend the rays and focus them on the retina at the back of the eye. The retina is a thin layer of tissue at the back of the eye that contains millions of tiny light-sensing nerve cells called rods and cones, which are named for their distinct shapes. Cones are concentrated in the center of the retina, in an area called the macula. In bright light conditions, cones provide clear, sharp central vision and detect colors and fine details. Rods are located outside the macula and extend all the way to the outer edge of the retina. They provide peripheral or side vision. Rods also allow the eyes to detect motion and help us see in dim light and at night. These cells in the retina convert the light into electrical impulses. The optic nerve sends these impulses to the brain where an image is produced.

NAMA : DIRA PRATIWIKELAS : XII IPA 5ABSEN : 08HOW YOUR EYES WORKSThe human eye refracts light emitted off objects and onto the retina to bring the objects being viewed into focus. This involves many functions and processes.Step 1:Light rays pass through the eyes clear front cover called the cornea.Step 2:Light passes through the eyes pupil, the eyes window to the world. The pupil is surrounded by a sphincter call the iris; the eyes colored ring.Step 3:Light passes through the eyes crystalline lens, which constricts to help light rays come to focus at one focal point.Step 4:Light rays travel to and come to rest on the retina resulting in clear vision.Step 5:Once light rays come to rest on the retina a signal is carried done the optic nerve to the brain.Step 6:The brain receives the signals and interprets them into a picture(s).Step7:The brain tells the eyes what it sees by forming the picture.